In evolutionary biology, convergent evolution is the process whereby organisms not closely related (not monophyletic), independently evolve similar traits as a result of having to adapt to similar environments or ecological niches.

It is the opposite of divergent evolution, where related species evolve different traits.

On a molecular level, this can happen due to random mutation unrelated to adaptive changes; see long branch attraction. In cultural evolution, convergent evolution is the development of similar cultural adaptations to similar environmental conditions by different peoples with different ancestral cultures. An example of convergent evolution is the similar nature of the flight/wings of insects, birds, pterosaurs, and bats.

All four serve the same function and are similar in structure, but each evolved independently.

Human designers reuse designs that work well. Life forms also reuse certain structures (the camera eye, for example, appears in humans and octopuses). How well does this evidence support Darwinian evolution? Does it support intelligent design more strongly?

Evolutionary biologists attribute similar biological structures to either common descent or convergence. Structures are said to result from convergence if they evolved independently from distinct lines of organisms. Darwinian explanations of convergence strain credulity because they must account for how trial-and-error tinkering (natural selection acting on random variations) could produce strikingly similar structures in widely different organisms and environments. It’s one thing for evolution to explain similarity by common descent—the same structure is then just carried along in different lineages. It’s another to explain it as the result of blind tinkering that happened to hit on the same structure multiple times. Design proponents attribute such similar structures to common design (just as an engineer may use the same parts in different machines). If human designers frequently reuse successful designs, the designer of nature can surely do the same.

I’m a software engineer, and we re-use components all the time for different programs that have no “common ancestor”. E.g. – I can dump develop my String function library and use it in my web application and my Eclipse IDE plug-in, and those two Java programs have nothing in common. So you find the same bits in two different programs because I am the developer of both programs. But the two programs don’t extend from a common program that was used for some other purpose – they have no “common ancestor” program.

According to the standard mammalian phylogeny, the common ancestor of bats and whales was not capable of echolocation. Thus, the ability to echolocate must have evolved independently, and bat and whale echolocation is often cited by evolutionists as a textbook example of convergent evolution. However, the ScienceDaily article reports that these similarities are not just phenotypic but extend down into the level of the gene sequences:

two new studies in the January 26th issue of Current Biology, a Cell Press publication, show that bats’ and whales’ remarkable ability and the high-frequency hearing it depends on are shared at a much deeper level than anyone would have anticipated — all the way down to the molecular level

Just as I noted that convergent genetic evolution was said to be “surprising” under neo-Darwinian thinking, this article reports, “The discovery represents an unprecedented example of adaptive sequence convergence between two highly divergent groups and suggests that such convergence at the sequence level might be more common than scientists had suspected.”

The typical Darwinist tack is to call similar structures “superficially similar”. I.e. – the appearance (phenotypes) are similar, but at the genotype (code) level, there is nothing in common. They have to say that because there is no common ancestor who shares the structure, so the biological information CANNOT be similar. A naturalistic theory can’t accommodate similarities at the genetic level unless there is a shared common ancestor who has those instructions. But guess what? When you actually take a closer look at the evidence… the biological information IS similar between bats and whales – AND THEY DON’T SHARE A COMMON ANCESTOR. So it exactly like the software design scenario, where the designer has put the same bits into two programs that were developed independently and don’t extend from a common program.

“The natural world is full of examples of species that have evolved similar characteristics independently, such as the tusks of elephants and walruses,” said Stephen Rossiter of the University of London, an author on one of the studies. “However, it is generally assumed that most of these so-called convergent traits have arisen by different genes or different mutations. Our study shows that a complex trait — echolocation — has in fact evolved by identical genetic changes in bats and dolphins.”

[…]”We were surprised by the strength of support for convergence between these two groups of mammals and, related to this, by the sheer number of convergent changes in the coding DNA that we found,” Rossiter said.